diff mbox series

[OpenMP] Implement uses_allocators clause for target regions

Message ID 46d77e14-080c-db6c-4032-e12899c5d059@codesourcery.com
State New
Headers show
Series [OpenMP] Implement uses_allocators clause for target regions | expand

Commit Message

Chung-Lin Tang May 6, 2022, 1:20 p.m. UTC
Hi Jakub,
this patch implements the uses_allocators clause for OpenMP target regions.

For user defined allocator handles, this allows target regions to assign
memory space and traits to allocators, and automatically calls
omp_init/destroy_allocator() in the beginning/end of the target region.

For pre-defined allocators (i.e. omp_..._mem_alloc names), this is a no-op,
such clauses are not created.

Asides from the front-end portions, the target region transforms are
done in gimplify_omp_workshare.

This patch also includes added changes to enforce the "allocate allocator
must be also in a uses_allocator clause", as to mentioned in[1].
This is done during gimplify_scan_omp_clauses.

[1] https://gcc.gnu.org/pipermail/gcc-patches/2022-May/594039.html

Tested on mainline, please see if this is okay.

Thanks,
Chung-Lin

2022-05-06  Chung-Lin Tang  <cltang@codesourcery.com>

gcc/c-family/ChangeLog:

	* c-omp.cc (c_omp_split_clauses): Add OMP_CLAUSE_USES_ALLOCATORS case.
	* c-pragma.h (enum pragma_omp_clause): Add PRAGMA_OMP_CLAUSE_USES_ALLOCATORS.

gcc/c/ChangeLog:

	* c-parser.cc (c_parser_omp_clause_name): Add case for uses_allocators
	clause.
	(c_parser_omp_clause_uses_allocators): New function.
	(c_parser_omp_all_clauses): Add PRAGMA_OMP_CLAUSE_USES_ALLOCATORS case.
	(OMP_TARGET_CLAUSE_MASK): Add PRAGMA_OMP_CLAUSE_USES_ALLOCATORS to mask.
	* c-typeck.cc (c_finish_omp_clauses): Add case handling for
	OMP_CLAUSE_USES_ALLOCATORS.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_omp_clause_name): Add case for uses_allocators
	clause.
	(cp_parser_omp_clause_uses_allocators): New function.
	(cp_parser_omp_all_clauses): Add PRAGMA_OMP_CLAUSE_USES_ALLOCATORS case.
	(OMP_TARGET_CLAUSE_MASK): Add PRAGMA_OMP_CLAUSE_USES_ALLOCATORS to mask.
	* semantics.cc (finish_omp_clauses): Add case handling for
	OMP_CLAUSE_USES_ALLOCATORS.

fortran/ChangeLog:

	* gfortran.h (struct gfc_omp_namelist): Add memspace_sym, traits_sym
	fields.
	(OMP_LIST_USES_ALLOCATORS): New list enum.
	* openmp.cc (enum omp_mask2): Add OMP_CLAUSE_USES_ALLOCATORS.
	(gfc_match_omp_clause_uses_allocators): New function.
	(gfc_match_omp_clauses): Add case to handle OMP_CLAUSE_USES_ALLOCATORS.
	(OMP_TARGET_CLAUSES): Add OMP_CLAUSE_USES_ALLOCATORS.
	(resolve_omp_clauses): Add "USES_ALLOCATORS" to clause_names[].
	* trans-array.cc (gfc_conv_array_initializer): Adjust array index
	to always be a created tree expression instead of NULL_TREE when zero.
	* trans-openmp.cc (gfc_trans_omp_clauses): For ALLOCATE clause, handle
	using gfc_trans_omp_variable for EXPR_VARIABLE exprs.
	Add handling of OMP_LIST_USES_ALLOCATORS case.
	* types.def (BT_FN_VOID_PTRMODE): Define.
	(BT_FN_PTRMODE_PTRMODE_INT_PTR): Define.

gcc/ChangeLog:

	* builtin-types.def (BT_FN_VOID_PTRMODE): Define.
	(BT_FN_PTRMODE_PTRMODE_INT_PTR): Define.
	* omp-builtins.def (BUILT_IN_OMP_INIT_ALLOCATOR): Define.
	(BUILT_IN_OMP_DESTROY_ALLOCATOR): Define.
	* tree-core.h (enum omp_clause_code): Add OMP_CLAUSE_USES_ALLOCATORS.
	* tree-pretty-print.cc (dump_omp_clause): Handle OMP_CLAUSE_USES_ALLOCATORS.
	* tree.h (OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR): New macro.
	(OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE): New macro.
	(OMP_CLAUSE_USES_ALLOCATORS_TRAITS): New macro.
	* tree.cc (omp_clause_num_ops): Add OMP_CLAUSE_USES_ALLOCATORS.
	(omp_clause_code_name): Add "uses_allocators".

	* gimplify.cc (gimplify_scan_omp_clauses): Add checking of OpenMP target
	region allocate	clauses, to require a uses_allocators clause to exist
	for allocators.
	(gimplify_omp_workshare): Add handling of OMP_CLAUSE_USES_ALLOCATORS
	for OpenMP target regions; create calls of omp_init/destroy_allocator
	around target region body.

gcc/testsuite/ChangeLog:

	* c-c++-common/gomp/uses_allocators-1.c: New test.
	* c-c++-common/gomp/uses_allocators-2.c: New test.
	* gfortran.dg/gomp/uses_allocators-1.f90: New test.
	* gfortran.dg/gomp/uses_allocators-2.f90: New test.
	* gfortran.dg/gomp/uses_allocators-3.f90: New test.

Comments

Tobias Burnus May 6, 2022, 4:40 p.m. UTC | #1
Hi Chung-Lin,

thanks for the patch – and some comments from my side.

On 06.05.22 15:20, Chung-Lin Tang wrote:
> For user defined allocator handles, this allows target regions to assign
> memory space and traits to allocators, and automatically calls
> omp_init/destroy_allocator() in the beginning/end of the target region.

Can please also handle the new clause in Fortran's dump-parse-tree.cc?

I did see some split handling in C, but not in Fortran; do you also need
to up update gfc_split_omp_clauses in Fortran's trans-openmp.cc?

Actually, glancing at the testcases, no combined construct (like
"omp target parallel") is used, I think that would be useful because of ↑.

> +/* OpenMP 5.2:
> +   uses_allocators ( allocator-list )
That's not completely true: uses_allocators is OpenMP 5.1.
However, 5.1 only supports (for non-predefined allocators):
    uses_allocators( allocator(traits) )
while OpenMP 5.2 added modifiers:
    uses_allocatrors( traits(...), memspace(...) : allocator )
and deprecated the 5.1 'allocator(traits)'. (Scheduled for removal in OMP 6.0)

The advantage of 5.2 syntax is that a memory space can be defined.

BTW: This makes uses_allocators the first OpenMP 5.2 feature which
will make it into GCC :-)


gcc/fortran/openmp.cc:
> +  if (gfc_get_symbol ("omp_allocator_handle_kind", NULL, &sym)
> +      || !sym->value
> +      || sym->value->expr_type != EXPR_CONSTANT
> +      || sym->value->ts.type != BT_INTEGER)
> +    {
> +      gfc_error ("OpenMP %<omp_allocator_handle_kind%> constant not found by "
> +              "%<uses_allocators%> clause at %C");
> +      goto error;
> +    }
> +  allocator_handle_kind = sym;
I think you rather want to use
   gfc_find_symbol ("omp_...", NULL, true, &sym)
   || sym == NULL
where true is for parent_flag to search also the parent namespace.
(The function returns 1 if the symbol is ambiguous, 0 otherwise -
including 0 + sym == NULL when the symbol could not be found.)

   || sym->attr.flavor != FL_PARAMETER
   || sym->ts.type != BT_INTEGER
   || sym->attr.dimension

Looks cleaner than to access sym->value. The attr.dimension is just
to makes sure the user did not smuggle an array into this.
(Invalid as omp_... is a reserved namespace but users will still do
this and some are good in finding ICE as hobby.)

  * * *

However, I fear that will fail for the following two examples (both untested):

   use omp_lib, my_kind = omp_allocator_handle_kind
   integer(my_kind) :: my_allocator

as this gives 'my_kind' in the symtree->name (while symtree->n.sym->name is "omp_...").
Hence, by searching the symtree for 'omp_...' the symbol will not be found.


It will likely also fail for the following more realistic example:

module m
   use omp_lib
   implicit none
   private
   integer(omp_allocator_handle_kind), public :: my_allocator
   type(omp_alloctrait), public, parameter :: my_traits(*) = [...]
end module

subroutine foo
   use m
   use omp_lib, only: omp_alloctrait
   implicit none
   ! currently, same scope is required - makes sense for C and 'const' but
   ! not for Fortran's parameters; restriction might be lifted/clarified in
   ! next OpenMP version:
   type(omp_alloctrait), parameter :: traits_array(*) = my_traits
   integer :: A(200)
   A = 0
   !$omp target uses_allocators(my_allocator(traits_array) allocate(my_allocator:A) firstprivate(A)
      ...
   !$omp end target
end

In this case, omp_allocator_handle_kind is not in the namespace of 'foo'
but the code should be still valid. Thus, an alternative would be to hard-code
the value - as done for the depobj. As we have:

         integer, parameter :: omp_allocator_handle_kind = c_intptr_t
         integer, parameter :: omp_memspace_handle_kind = c_intptr_t

that would be
    sym->ts.type == BT_CHARACTER
    sym->ts.kind == gfc_index_integer_kind
for the allocator variable and the the memspace kind.

However, I grant that either example is not very typical. The second one is more
natural – such a code will very likely be written in the real world. But not
with uses_allocators but rather with "!$omp requires dynamic_allocators" and
omp_init_allocator().

Thoughts?

* * *

gcc/fortran/openmp.cc
> +      if (++i > 2)
> +     {
> +       gfc_error ("Only two modifiers are allowed on %<uses_allocators%> "
> +                  "clause at %C");
> +       goto error;
> +     }
> +

Is this really needed? There is a check for multiple traits and multiple memspace
Thus, 'trait(),memspace(),trait()' is already handled and
'trait(),something' give a break and will lead to an error as in that case
a ':' and not ',something' is expected.

> +      if (gfc_match_char ('(') == MATCH_YES)
> +     {
> +       if (memspace_seen || traits_seen)
> +         {
> +           gfc_error ("Modifiers cannot be used with legacy "
> +                      "array syntax at %C");
I wouldn't uses the term 'array synax' to denote
   uses_allocators(allocator (alloc_array) )
How about:
   error: "Using both modifiers and allocator variable with traits argument"

(And I think 'deprecated' is better than 'legacy', if we really want to use it.)


> +       if (traits_sym->ts.type != BT_DERIVED
> +           || strcmp (traits_sym->ts.u.derived->name,
> +                      "omp_alloctrait") != 0
> +           || traits_sym->attr.flavor != FL_PARAMETER
> +           || traits_sym->as->rank != 1
> +           || traits_sym->value == NULL
> +           || !gfc_is_constant_expr (traits_sym->value))

I think the gfc_is_constant_expr is unreachable as you already
have checked FL_PARAMETER. Thus, you can remove the last two
lines.

[Regarding the traits_sym->ts.u.derived->name, I am not sure whether that
won't fail with
   use omp_lib, trait_t => omp_alloctrait
but I have not checked. It likely does work correctly.]

> +           /* Check if identifier is of 'omp_..._mem_space' format.  */
> +           || (pos = strstr (memspace_sym->name, "omp_")) == NULL
> +           || pos != memspace_sym->name
> +           || (pos = strstr (memspace_sym->name, "_mem_space")) == NULL
> +           || *(pos + strlen ("_mem_space")) != '\0')

I wonder whether that's not more readable written as:
    || !startswith (memspace_sym->name, "omp_")
    || !endswith (memspace_sym->name, "_mem_space")


Tobias

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diff mbox series

Patch

diff --git a/gcc/builtin-types.def b/gcc/builtin-types.def
index 3a7cecdf087..be3e6ff697e 100644
--- a/gcc/builtin-types.def
+++ b/gcc/builtin-types.def
@@ -283,6 +283,7 @@  DEF_FUNCTION_TYPE_1 (BT_FN_DFLOAT32_DFLOAT32, BT_DFLOAT32, BT_DFLOAT32)
 DEF_FUNCTION_TYPE_1 (BT_FN_DFLOAT64_DFLOAT64, BT_DFLOAT64, BT_DFLOAT64)
 DEF_FUNCTION_TYPE_1 (BT_FN_DFLOAT128_DFLOAT128, BT_DFLOAT128, BT_DFLOAT128)
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_VPTR, BT_VOID, BT_VOLATILE_PTR)
+DEF_FUNCTION_TYPE_1 (BT_FN_VOID_PTRMODE, BT_VOID, BT_PTRMODE)
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_PTRPTR, BT_VOID, BT_PTR_PTR)
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_CONST_PTR, BT_VOID, BT_CONST_PTR)
 DEF_FUNCTION_TYPE_1 (BT_FN_UINT_UINT, BT_UINT, BT_UINT)
@@ -641,6 +642,8 @@  DEF_FUNCTION_TYPE_3 (BT_FN_PTR_SIZE_SIZE_PTRMODE,
 		     BT_PTR, BT_SIZE, BT_SIZE, BT_PTRMODE)
 DEF_FUNCTION_TYPE_3 (BT_FN_VOID_PTR_UINT8_PTRMODE, BT_VOID, BT_PTR, BT_UINT8,
 		     BT_PTRMODE)
+DEF_FUNCTION_TYPE_3 (BT_FN_PTRMODE_PTRMODE_INT_PTR, BT_PTRMODE, BT_PTRMODE,
+		     BT_INT, BT_PTR)
 
 DEF_FUNCTION_TYPE_4 (BT_FN_SIZE_CONST_PTR_SIZE_SIZE_FILEPTR,
 		     BT_SIZE, BT_CONST_PTR, BT_SIZE, BT_SIZE, BT_FILEPTR)
diff --git a/gcc/c-family/c-omp.cc b/gcc/c-family/c-omp.cc
index 777cdc65572..5066e137cf4 100644
--- a/gcc/c-family/c-omp.cc
+++ b/gcc/c-family/c-omp.cc
@@ -1870,6 +1870,7 @@  c_omp_split_clauses (location_t loc, enum tree_code code,
 	case OMP_CLAUSE_HAS_DEVICE_ADDR:
 	case OMP_CLAUSE_DEFAULTMAP:
 	case OMP_CLAUSE_DEPEND:
+	case OMP_CLAUSE_USES_ALLOCATORS:
 	  s = C_OMP_CLAUSE_SPLIT_TARGET;
 	  break;
 	case OMP_CLAUSE_NUM_TEAMS:
diff --git a/gcc/c-family/c-pragma.h b/gcc/c-family/c-pragma.h
index 54864c2ec41..7f8944f81d6 100644
--- a/gcc/c-family/c-pragma.h
+++ b/gcc/c-family/c-pragma.h
@@ -154,6 +154,7 @@  enum pragma_omp_clause {
   PRAGMA_OMP_CLAUSE_UNTIED,
   PRAGMA_OMP_CLAUSE_USE_DEVICE_PTR,
   PRAGMA_OMP_CLAUSE_USE_DEVICE_ADDR,
+  PRAGMA_OMP_CLAUSE_USES_ALLOCATORS,
 
   /* Clauses for OpenACC.  */
   PRAGMA_OACC_CLAUSE_ASYNC,
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index 129dd727ef3..2befad91158 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -12907,6 +12907,8 @@  c_parser_omp_clause_name (c_parser *parser)
 	    result = PRAGMA_OMP_CLAUSE_USE_DEVICE_ADDR;
 	  else if (!strcmp ("use_device_ptr", p))
 	    result = PRAGMA_OMP_CLAUSE_USE_DEVICE_PTR;
+	  else if (!strcmp ("uses_allocators", p))
+	    result = PRAGMA_OMP_CLAUSE_USES_ALLOCATORS;
 	  break;
 	case 'v':
 	  if (!strcmp ("vector", p))
@@ -15624,6 +15626,225 @@  c_parser_omp_clause_allocate (c_parser *parser, tree list)
   return nl;
 }
 
+/* OpenMP 5.2:
+   uses_allocators ( allocator-list )
+
+   allocator-list:
+   allocator
+   allocator , allocator-list
+   allocator ( traits-array )
+   allocator ( traits-array ) , allocator-list
+
+   uses_allocators ( modifier : allocator )
+   uses_allocators ( modifier , modifier : allocator )
+
+   modifier:
+   traits ( traits-array )
+   memspace ( mem-space-handle )  */
+
+static tree
+c_parser_omp_clause_uses_allocators (c_parser *parser, tree list)
+{
+  location_t clause_loc = c_parser_peek_token (parser)->location;
+  tree nl;
+  matching_parens parens;
+  if (!parens.require_open (parser))
+    return list;
+
+  bool has_modifiers = false;
+  tree memspace_expr = NULL_TREE;
+  tree traits_var = NULL_TREE;
+
+  if (c_parser_next_token_is (parser, CPP_NAME))
+    {
+      c_token *tok = c_parser_peek_token (parser);
+      const char *p = IDENTIFIER_POINTER (tok->value);
+
+      if (strcmp ("traits", p) == 0 || strcmp ("memspace", p) == 0)
+	{
+	  has_modifiers = true;
+	  c_parser_consume_token (parser);
+	  matching_parens parens2;;
+	  parens2.require_open (parser);
+
+	  if (c_parser_next_token_is (parser, CPP_NAME)
+	      && (c_parser_peek_token (parser)->id_kind == C_ID_ID
+		  || c_parser_peek_token (parser)->id_kind == C_ID_TYPENAME))
+	    {
+	      tok = c_parser_peek_token (parser);
+	      tree t = lookup_name (tok->value);
+
+	      if (t == NULL_TREE)
+		{
+		  undeclared_variable (tok->location, tok->value);
+		  t = error_mark_node;
+		}
+	      else
+		{
+		  if (strcmp ("memspace", p) == 0)
+		    memspace_expr = t;
+		  else
+		    traits_var = t;
+		}
+	      c_parser_consume_token (parser);
+	    }
+
+	  parens2.skip_until_found_close (parser);
+
+	  if (c_parser_next_token_is (parser, CPP_COMMA))
+	    {
+	      c_parser_consume_token (parser);
+	      tok = c_parser_peek_token (parser);
+	      const char *q = "";
+	      if (c_parser_next_token_is (parser, CPP_NAME))
+		q = IDENTIFIER_POINTER (tok->value);
+	      if (strcmp (q, "memspace") != 0 && strcmp (q, "traits") != 0)
+		{
+		  c_parser_error (parser, "expected %<memspace%> or %<traits%>");
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+	      else if (strcmp (p, q) == 0)
+		{
+		  error_at (tok->location, "duplicate %qs modifier", p);
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+	      c_parser_consume_token (parser);
+	      if (!parens2.require_open (parser))
+		{
+		  parens.skip_until_found_close (parser);
+		  return list;
+		}
+
+	      if (c_parser_next_token_is (parser, CPP_NAME)
+		  && (c_parser_peek_token (parser)->id_kind == C_ID_ID
+		      || c_parser_peek_token (parser)->id_kind == C_ID_TYPENAME))
+		{
+		  tok = c_parser_peek_token (parser);
+		  tree t = lookup_name (tok->value);
+		  if (t == NULL_TREE)
+		    {
+		      undeclared_variable (tok->location, tok->value);
+		      t = error_mark_node;
+		    }
+		  else
+		    {
+		      if (strcmp ("memspace", q) == 0)
+			memspace_expr = t;
+		      else
+			traits_var = t;
+		    }
+		  c_parser_consume_token (parser);
+		}
+	      parens2.skip_until_found_close (parser);
+	    }
+	}
+    }
+
+  if (has_modifiers)
+    {
+      if (!c_parser_require (parser, CPP_COLON, "expected %<:%>"))
+	{
+	  parens.skip_until_found_close (parser);
+	  return list;
+	}
+
+      if (c_parser_next_token_is (parser, CPP_NAME)
+	  && c_parser_peek_token (parser)->id_kind == C_ID_ID)
+	{
+	  tree t = lookup_name (c_parser_peek_token (parser)->value);
+
+	  if (t == NULL_TREE)
+	    {
+	      undeclared_variable (c_parser_peek_token (parser)->location,
+				   c_parser_peek_token (parser)->value);
+	      t = error_mark_node;
+	    }
+	  else if (t != error_mark_node)
+	    {
+	      tree c = build_omp_clause (clause_loc,
+					 OMP_CLAUSE_USES_ALLOCATORS);
+	      OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c) = t;
+	      OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c) = memspace_expr;
+	      OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c) = traits_var;
+	      OMP_CLAUSE_CHAIN (c) = list;
+
+	      nl = c;
+	    }
+	  c_parser_consume_token (parser);
+
+	  if (c_parser_next_token_is (parser, CPP_OPEN_PAREN))
+	    c_parser_error (parser, "modifiers cannot be used with "
+			    "legacy array syntax");
+	}
+      else
+	c_parser_error (parser, "expected identifier");
+    }
+  else
+    {
+      traits_var = NULL_TREE;
+
+      nl = list;
+      while (true)
+	{
+	  if (c_parser_next_token_is (parser, CPP_NAME)
+	      && c_parser_peek_token (parser)->id_kind == C_ID_ID)
+	    {
+	      c_token *tok = c_parser_peek_token (parser);
+	      tree t = lookup_name (tok->value);
+
+	      if (t == NULL_TREE)
+		{
+		  undeclared_variable (tok->location, tok->value);
+		  break;
+		}
+	      else if (t == error_mark_node)
+		break;
+
+	      c_parser_consume_token (parser);
+
+	      if (c_parser_next_token_is (parser, CPP_OPEN_PAREN))
+		{
+		  matching_parens parens2;
+		  parens2.consume_open (parser);
+		  if (c_parser_next_token_is (parser, CPP_NAME)
+		      && c_parser_peek_token (parser)->id_kind == C_ID_ID)
+		    {
+		      tok = c_parser_peek_token (parser);
+		      traits_var = lookup_name (tok->value);
+		      if (traits_var == NULL_TREE)
+			{
+			  undeclared_variable (tok->location, tok->value);
+			  break;
+			}
+		      c_parser_consume_token (parser);
+		    }
+		  else
+		    c_parser_error (parser, "expected identifier");
+		  parens2.require_close (parser);
+		}
+
+	      tree c = build_omp_clause (clause_loc,
+					 OMP_CLAUSE_USES_ALLOCATORS);
+	      OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c) = t;
+	      OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c) = NULL_TREE;
+	      OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c) = traits_var;
+	      OMP_CLAUSE_CHAIN (c) = nl;
+
+	      nl = c;
+	    }
+
+	  if (c_parser_next_token_is_not (parser, CPP_COMMA))
+	    break;
+	  c_parser_consume_token (parser);
+	}
+    }
+
+  parens.skip_until_found_close (parser);
+  return nl;
+}
+
 /* OpenMP 4.0:
    linear ( variable-list )
    linear ( variable-list : expression )
@@ -17050,6 +17271,10 @@  c_parser_omp_all_clauses (c_parser *parser, omp_clause_mask mask,
 	  clauses = c_parser_omp_clause_allocate (parser, clauses);
 	  c_name = "allocate";
 	  break;
+	case PRAGMA_OMP_CLAUSE_USES_ALLOCATORS:
+	  clauses = c_parser_omp_clause_uses_allocators (parser, clauses);
+	  c_name = "uses_allocators";
+	  break;
 	case PRAGMA_OMP_CLAUSE_LINEAR: 
 	  clauses = c_parser_omp_clause_linear (parser, clauses); 
 	  c_name = "linear";
@@ -21061,7 +21286,8 @@  c_parser_omp_target_exit_data (location_t loc, c_parser *parser,
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_IN_REDUCTION)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_THREAD_LIMIT)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_IS_DEVICE_PTR)\
-	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_HAS_DEVICE_ADDR))
+	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_HAS_DEVICE_ADDR)\
+	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_USES_ALLOCATORS))
 
 static bool
 c_parser_omp_target (c_parser *parser, enum pragma_context context, bool *if_p)
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index e130196a3a7..0e1f33b655d 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -14763,6 +14763,102 @@  c_finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	    }
 	  break;
 
+	case OMP_CLAUSE_USES_ALLOCATORS:
+	  t = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+	  if (bitmap_bit_p (&generic_head, DECL_UID (t))
+	      || bitmap_bit_p (&map_head, DECL_UID (t))
+	      || bitmap_bit_p (&firstprivate_head, DECL_UID (t))
+	      || bitmap_bit_p (&lastprivate_head, DECL_UID (t)))
+	    {
+	      error_at (OMP_CLAUSE_LOCATION (c),
+			"%qE appears more than once in data clauses", t);
+	      remove = true;
+	    }
+	  else
+	    bitmap_set_bit (&generic_head, DECL_UID (t));
+	  if (TREE_CODE (TREE_TYPE (t)) != ENUMERAL_TYPE
+	      || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (TREE_TYPE (t))),
+			 "omp_allocator_handle_t") != 0)
+	    {
+	      error_at (OMP_CLAUSE_LOCATION (c),
+			"allocator must be of %<omp_allocator_handle_t%> type");
+	      remove = true;
+	    }
+	  if (TREE_CODE (t) == CONST_DECL)
+	    {
+	      if (OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c)
+		  || OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c))
+		error_at (OMP_CLAUSE_LOCATION (c),
+			  "modifiers cannot be used with pre-defined "
+			  "allocators");
+
+	      /* Currently for pre-defined allocators in libgomp, we do not
+		 require additional init/fini inside target regions, so discard
+		 such clauses.  */
+	      remove = true;
+	    }
+	  t = OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c);
+	  if (t != NULL_TREE
+	      && (TREE_CODE (t) != CONST_DECL
+		  || TREE_CODE (TREE_TYPE (t)) != ENUMERAL_TYPE
+		  || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (TREE_TYPE (t))),
+			     "omp_memspace_handle_t") != 0))
+	    {
+	      error_at (OMP_CLAUSE_LOCATION (c), "memspace modifier must be "
+			"constant enum of %<omp_memspace_handle_t%> type");
+	      remove = true;
+	    }
+	  t = OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c);
+	  if (t != NULL_TREE)
+	    {
+	      bool type_err = false;
+
+	      if (TREE_CODE (TREE_TYPE (t)) != ARRAY_TYPE)
+		type_err = true;
+	      else
+		{
+		  tree elem_t = TREE_TYPE (TREE_TYPE (t));
+		  if (TREE_CODE (elem_t) != RECORD_TYPE
+		      || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (elem_t)),
+				 "omp_alloctrait_t") != 0
+		      || !TYPE_READONLY (elem_t))
+		    type_err = true;
+		}
+	      if (type_err)
+		{
+		  error_at (OMP_CLAUSE_LOCATION (c), "traits array must be of "
+			    "%<const omp_alloctrait_t []%> type");
+		  remove = true;
+		}
+	      else
+		{
+		  tree cst_val = decl_constant_value_1 (t, true);
+		  if (cst_val == t)
+		    {
+		      error_at (OMP_CLAUSE_LOCATION (c), "traits array must be "
+				"of constant values");
+
+		      remove = true;
+		    }
+		}
+	    }
+
+	  if (remove)
+	    break;
+	  else
+	    {
+	      /* Create a private clause for the allocator variable, placed
+		 prior to current uses_allocators clause.  */
+	      tree nc = build_omp_clause (OMP_CLAUSE_LOCATION (c),
+					  OMP_CLAUSE_PRIVATE);
+	      OMP_CLAUSE_DECL (nc) = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+	      OMP_CLAUSE_CHAIN (nc) = c;
+	      *pc = nc;
+
+	      pc = &OMP_CLAUSE_CHAIN (c);
+	      continue;
+	    }
+
 	case OMP_CLAUSE_DEPEND:
 	  t = OMP_CLAUSE_DECL (c);
 	  if (t == NULL_TREE)
diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 2235da10c7c..143c70d0b49 100644
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -36490,6 +36490,8 @@  cp_parser_omp_clause_name (cp_parser *parser)
 	    result = PRAGMA_OMP_CLAUSE_USE_DEVICE_ADDR;
 	  else if (!strcmp ("use_device_ptr", p))
 	    result = PRAGMA_OMP_CLAUSE_USE_DEVICE_PTR;
+	  else if (!strcmp ("uses_allocators", p))
+	    result = PRAGMA_OMP_CLAUSE_USES_ALLOCATORS;
 	  break;
 	case 'v':
 	  if (!strcmp ("vector", p))
@@ -38733,6 +38735,246 @@  cp_parser_omp_clause_allocate (cp_parser *parser, tree list)
   return nlist;
 }
 
+/* OpenMP 5.2:
+   uses_allocators ( allocator-list )
+
+   allocator-list:
+   allocator
+   allocator , allocator-list
+   allocator ( traits-array )
+   allocator ( traits-array ) , allocator-list
+
+   uses_allocators ( modifier : allocator )
+   uses_allocators ( modifier , modifier : allocator )
+
+   modifier:
+   traits ( traits-array )
+   memspace ( mem-space-handle )  */
+
+static tree
+cp_parser_omp_clause_uses_allocators (cp_parser *parser, tree list)
+{
+  location_t clause_loc
+    = cp_lexer_peek_token (parser->lexer)->location;
+  tree t = NULL_TREE, nl;
+  matching_parens parens;
+  if (!parens.require_open (parser))
+    return list;
+
+  bool has_modifiers = false;
+  tree memspace_expr = NULL_TREE;
+  tree traits_var = NULL_TREE;
+
+  if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+    {
+      cp_token *tok = cp_lexer_peek_token (parser->lexer);
+      const char *p = IDENTIFIER_POINTER (tok->u.value);
+
+      if (strcmp ("traits", p) == 0 || strcmp ("memspace", p) == 0)
+	{
+	  has_modifiers = true;
+	  cp_lexer_consume_token (parser->lexer);
+	  matching_parens parens2;;
+	  parens2.require_open (parser);
+
+	  if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+	    {
+	      tok = cp_lexer_peek_token (parser->lexer);
+	      tree id = tok->u.value;
+
+	      t = cp_parser_lookup_name_simple (parser, id, tok->location);
+	      if (t == error_mark_node)
+		cp_parser_name_lookup_error (parser, id, t, NLE_NULL,
+					     tok->location);
+	      else
+		{
+		  if (strcmp ("memspace", p) == 0)
+		    memspace_expr = t;
+		  else
+		    traits_var = t;
+		}
+	      cp_lexer_consume_token (parser->lexer);
+	    }
+
+	  if (t == error_mark_node || !parens.require_close (parser))
+	    {
+	      cp_parser_skip_to_closing_parenthesis (parser,
+						     /*recovering=*/true,
+						     /*or_comma=*/false,
+						     /*consume_paren=*/true);
+	      return list;
+	    }
+
+	  if (cp_lexer_next_token_is (parser->lexer, CPP_COMMA))
+	    {
+	      cp_lexer_consume_token (parser->lexer);
+	      tok = cp_lexer_peek_token (parser->lexer);
+	      const char *q = "";
+
+	      if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+		q = IDENTIFIER_POINTER (tok->u.value);
+
+	      if (strcmp (q, "memspace") != 0 && strcmp (q, "traits") != 0)
+		{
+		  cp_parser_error (parser, "expected %<memspace%> or %<traits%>");
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/true);
+		  return list;
+		}
+	      else if (strcmp (p, q) == 0)
+		{
+		  error_at (tok->location, "duplicate %qs modifier", p);
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/true);
+		  return list;
+		}
+	      cp_lexer_consume_token (parser->lexer);
+	      if (!parens2.require_open (parser))
+		{
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/true);
+		  return list;
+		}
+
+	      if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+		{
+		  tok = cp_lexer_peek_token (parser->lexer);
+		  tree id = tok->u.value;
+
+		  t = cp_parser_lookup_name_simple (parser, id, tok->location);
+		  if (t == error_mark_node)
+		    cp_parser_name_lookup_error (parser, id, t, NLE_NULL,
+						 tok->location);
+		  else
+		    {
+		      if (strcmp ("memspace", q) == 0)
+			memspace_expr = t;
+		      else
+			traits_var = t;
+		    }
+		  cp_lexer_consume_token (parser->lexer);
+		}
+
+	      if (t == error_mark_node || !parens.require_close (parser))
+		{
+		  cp_parser_skip_to_closing_parenthesis (parser,
+							 /*recovering=*/true,
+							 /*or_comma=*/false,
+							 /*consume_paren=*/true);
+		  return list;
+		}
+	    }
+
+	}
+    }
+
+  if (has_modifiers)
+    {
+      if (!cp_parser_require (parser, CPP_COLON, RT_COLON))
+	{
+	  cp_parser_skip_to_closing_parenthesis (parser, /*recovering=*/true,
+						 /*or_comma=*/false,
+						 /*consume_paren=*/true);
+	  return list;
+	}
+
+      if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+	{
+	  cp_token *tok = cp_lexer_peek_token (parser->lexer);
+	  tree id = tok->u.value;
+	  tree t = cp_parser_lookup_name_simple (parser, id, tok->location);
+
+	  if (t == error_mark_node)
+	    cp_parser_name_lookup_error (parser, id, t, NLE_NULL,
+					 tok->location);
+	  else
+	    {
+	      tree c = build_omp_clause (clause_loc,
+					 OMP_CLAUSE_USES_ALLOCATORS);
+	      OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c) = t;
+	      OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c) = memspace_expr;
+	      OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c) = traits_var;
+	      OMP_CLAUSE_CHAIN (c) = list;
+
+	      nl = c;
+	    }
+	  cp_lexer_consume_token (parser->lexer);
+
+	  if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_PAREN))
+	    cp_parser_error (parser, "modifiers cannot be used with "
+			     "legacy array syntax");
+	}
+      else
+	cp_parser_error (parser, "expected identifier");
+    }
+  else
+    {
+      traits_var = NULL_TREE;
+
+      nl = list;
+      while (true)
+	{
+	  if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+	    {
+	      cp_token *tok = cp_lexer_peek_token (parser->lexer);
+	      tree id = tok->u.value;
+
+	      tree t = cp_parser_lookup_name_simple (parser, id, tok->location);
+
+	      if (t == error_mark_node)
+		cp_parser_name_lookup_error (parser, id, t, NLE_NULL,
+					     tok->location);
+	      cp_lexer_consume_token (parser->lexer);
+
+	      if (cp_lexer_next_token_is (parser->lexer, CPP_OPEN_PAREN))
+		{
+		  matching_parens parens2;
+		  parens2.consume_open (parser);
+		  if (cp_lexer_next_token_is (parser->lexer, CPP_NAME))
+		    {
+		      tok = cp_lexer_peek_token (parser->lexer);
+		      id = tok->u.value;
+		      traits_var = cp_parser_lookup_name_simple (parser, id,
+								 tok->location);
+		      if (traits_var == error_mark_node)
+			{
+			  cp_parser_name_lookup_error (parser, id, traits_var,
+						       NLE_NULL, tok->location);
+			  break;
+			}
+		      cp_lexer_consume_token (parser->lexer);
+		    }
+		  else
+		    cp_parser_error (parser, "expected identifier");
+		  parens2.require_close (parser);
+		}
+
+	      tree c = build_omp_clause (clause_loc,
+					 OMP_CLAUSE_USES_ALLOCATORS);
+	      OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c) = t;
+	      OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c) = NULL_TREE;
+	      OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c) = traits_var;
+	      OMP_CLAUSE_CHAIN (c) = nl;
+
+	      nl = c;
+	    }
+
+	  if (cp_lexer_next_token_is_not (parser->lexer, CPP_COMMA))
+	    break;
+	  cp_lexer_consume_token (parser->lexer);
+	}
+    }
+
+  parens.require_close (parser);
+  return nl;
+}
+
 /* OpenMP 2.5:
    lastprivate ( variable-list )
 
@@ -40283,6 +40525,10 @@  cp_parser_omp_all_clauses (cp_parser *parser, omp_clause_mask mask,
 	  clauses = cp_parser_omp_clause_allocate (parser, clauses);
 	  c_name = "allocate";
 	  break;
+	case PRAGMA_OMP_CLAUSE_USES_ALLOCATORS:
+	  clauses = cp_parser_omp_clause_uses_allocators (parser, clauses);
+	  c_name = "uses_allocators";
+	  break;
 	case PRAGMA_OMP_CLAUSE_LINEAR:
 	  {
 	    bool declare_simd = false;
@@ -44291,7 +44537,8 @@  cp_parser_omp_target_update (cp_parser *parser, cp_token *pragma_tok,
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_IN_REDUCTION)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_THREAD_LIMIT)	\
 	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_IS_DEVICE_PTR)\
-	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_HAS_DEVICE_ADDR))
+	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_HAS_DEVICE_ADDR)\
+	| (OMP_CLAUSE_MASK_1 << PRAGMA_OMP_CLAUSE_USES_ALLOCATORS))
 
 static bool
 cp_parser_omp_target (cp_parser *parser, cp_token *pragma_tok,
diff --git a/gcc/cp/semantics.cc b/gcc/cp/semantics.cc
index 377f61113c0..ac8c4b2e3e9 100644
--- a/gcc/cp/semantics.cc
+++ b/gcc/cp/semantics.cc
@@ -7772,6 +7772,90 @@  finish_omp_clauses (tree clauses, enum c_omp_region_type ort)
 	    }
 	  goto handle_field_decl;
 
+	case OMP_CLAUSE_USES_ALLOCATORS:
+	  t = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+	  if (TREE_CODE (TREE_TYPE (t)) != ENUMERAL_TYPE
+	      || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (TREE_TYPE (t))),
+			 "omp_allocator_handle_t") != 0)
+	    {
+	      error_at (OMP_CLAUSE_LOCATION (c),
+			"allocator must be of %<omp_allocator_handle_t%> type");
+	      remove = true;
+	    }
+	  if (TREE_CODE (t) == CONST_DECL)
+	    {
+	      if (OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c)
+		  || OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c))
+		error_at (OMP_CLAUSE_LOCATION (c),
+			  "modifiers cannot be used with pre-defined "
+			  "allocators");
+
+	      /* Currently for pre-defined allocators in libgomp, we do not
+		 require additional init/fini inside target regions, so discard
+		 such clauses.  */
+	      remove = true;
+	    }
+	  t = OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c);
+	  if (t != NULL_TREE
+	      && (TREE_CODE (t) != CONST_DECL
+		  || TREE_CODE (TREE_TYPE (t)) != ENUMERAL_TYPE
+		  || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (TREE_TYPE (t))),
+			     "omp_memspace_handle_t") != 0))
+	    {
+	      error_at (OMP_CLAUSE_LOCATION (c), "memspace modifier must be "
+			"constant enum of %<omp_memspace_handle_t%> type");
+	      remove = true;
+	    }
+	  t = OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c);
+	  if (t != NULL_TREE)
+	    {
+	      bool type_err = false;
+
+	      if (TREE_CODE (TREE_TYPE (t)) != ARRAY_TYPE)
+		type_err = true;
+	      else
+		{
+		  tree elem_t = TREE_TYPE (TREE_TYPE (t));
+		  if (TREE_CODE (elem_t) != RECORD_TYPE
+		      || strcmp (IDENTIFIER_POINTER (TYPE_IDENTIFIER (elem_t)),
+				 "omp_alloctrait_t") != 0
+		      || !TYPE_READONLY (elem_t))
+		    type_err = true;
+		}
+	      if (type_err)
+		{
+		  error_at (OMP_CLAUSE_LOCATION (c), "traits array must be of "
+			    "%<const omp_alloctrait_t []%> type");
+		  remove = true;
+		}
+	      else
+		{
+		  tree cst_val = decl_constant_value (t);
+		  if (cst_val == t)
+		    {
+		      error_at (OMP_CLAUSE_LOCATION (c), "traits array must be "
+				"of constant values");
+
+		      remove = true;
+		    }
+		}
+	    }
+	  if (remove)
+	    break;
+	  else
+	    {
+	      /* Create a private clause for the allocator variable, placed
+		 prior to current uses_allocators clause.  */
+	      tree nc = build_omp_clause (OMP_CLAUSE_LOCATION (c),
+					  OMP_CLAUSE_PRIVATE);
+	      OMP_CLAUSE_DECL (nc) = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+	      OMP_CLAUSE_CHAIN (nc) = c;
+	      *pc = nc;
+
+	      pc = &OMP_CLAUSE_CHAIN (c);
+	      continue;
+	    }
+
 	case OMP_CLAUSE_DEPEND:
 	  t = OMP_CLAUSE_DECL (c);
 	  if (t == NULL_TREE)
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 7bf1d5a0452..18e685ca1b1 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -1353,6 +1353,8 @@  typedef struct gfc_omp_namelist
       struct gfc_omp_namelist_udr *udr;
       gfc_namespace *ns;
     } u2;
+  struct gfc_symbol *memspace_sym;
+  struct gfc_symbol *traits_sym;
   struct gfc_omp_namelist *next;
   locus where;
 }
@@ -1394,6 +1396,7 @@  enum
   OMP_LIST_NONTEMPORAL,
   OMP_LIST_ALLOCATE,
   OMP_LIST_HAS_DEVICE_ADDR,
+  OMP_LIST_USES_ALLOCATORS,
   OMP_LIST_NUM /* Must be the last.  */
 };
 
diff --git a/gcc/fortran/openmp.cc b/gcc/fortran/openmp.cc
index 714148138c2..64066047a33 100644
--- a/gcc/fortran/openmp.cc
+++ b/gcc/fortran/openmp.cc
@@ -948,6 +948,7 @@  enum omp_mask2
   OMP_CLAUSE_ATTACH,
   OMP_CLAUSE_NOHOST,
   OMP_CLAUSE_HAS_DEVICE_ADDR,  /* OpenMP 5.1  */
+  OMP_CLAUSE_USES_ALLOCATORS,  /* OpenMP 5.2  */
   /* This must come last.  */
   OMP_MASK2_LAST
 };
@@ -1364,6 +1365,238 @@  gfc_match_omp_clause_reduction (char pc, gfc_omp_clauses *c, bool openacc,
   return MATCH_YES;
 }
 
+/* uses_allocators ( allocator-list )
+
+   allocator-list:
+   allocator
+   allocator , allocator-list
+   allocator ( traits-array )
+   allocator ( traits-array ) , allocator-list
+
+   uses_allocators ( modifier : allocator )
+   uses_allocators ( modifier , modifier : allocator )
+
+   modifier:
+   traits ( traits-array )
+   memspace ( mem-space-handle )  */
+
+static match
+gfc_match_omp_clause_uses_allocators (gfc_omp_clauses *c)
+{
+  gfc_symbol *sym;
+  gfc_symbol *memspace_sym= NULL;
+  gfc_symbol *traits_sym= NULL;
+  bool memspace_seen = false, traits_seen = false;
+  match m;
+  int i = 0;
+
+  if (gfc_match ("uses_allocators ( ") != MATCH_YES)
+    return MATCH_NO;
+
+  gfc_symbol *allocator_handle_kind, * memspace_handle_kind;
+
+  if (gfc_get_symbol ("omp_allocator_handle_kind", NULL, &sym)
+      || !sym->value
+      || sym->value->expr_type != EXPR_CONSTANT
+      || sym->value->ts.type != BT_INTEGER)
+    {
+      gfc_error ("OpenMP %<omp_allocator_handle_kind%> constant not found by "
+		 "%<uses_allocators%> clause at %C");
+      goto error;
+    }
+  allocator_handle_kind = sym;
+
+  if (gfc_get_symbol ("omp_memspace_handle_kind", NULL, &sym)
+      || !sym->value
+      || sym->value->expr_type != EXPR_CONSTANT
+      || sym->value->ts.type != BT_INTEGER)
+    {
+      gfc_error ("OpenMP %<omp_memspace_handle_kind%> constant not found by "
+		 "%<uses_allocators%> clause at %C");
+      goto error;
+    }
+  memspace_handle_kind = sym;
+
+  do
+    {
+      if (++i > 2)
+	{
+	  gfc_error ("Only two modifiers are allowed on %<uses_allocators%> "
+		     "clause at %C");
+	  goto error;
+	}
+
+      if (gfc_match ("memspace ( ") == MATCH_YES)
+	{
+	  if (memspace_seen)
+	    {
+	      gfc_error ("Multiple memspace modifiers at %C");
+	      goto error;
+	    }
+	  memspace_seen = true;
+	  m = gfc_match_symbol (&sym, 1);
+	  if (m == MATCH_YES)
+	    memspace_sym = sym;
+	  else
+	    goto error;
+	  if (gfc_match_char (')') != MATCH_YES)
+	    goto error;
+	}
+      else if (gfc_match ("traits ( ") == MATCH_YES)
+	{
+	  if (traits_seen)
+	    {
+	      gfc_error ("Multiple traits modifiers at %C");
+	      goto error;
+	    }
+	  traits_seen = true;
+	  m = gfc_match_symbol (&sym, 1);
+	  if (m == MATCH_YES)
+	    traits_sym = sym;
+	  else
+	    goto error;
+	  if (gfc_match_char (')') != MATCH_YES)
+	    goto error;
+	}
+      else
+	break;
+    }
+  while (gfc_match (" , ") == MATCH_YES);
+
+  if ((memspace_seen || traits_seen)
+      && gfc_match (" : ") != MATCH_YES)
+    goto error;
+
+  while (true)
+    {
+      m = gfc_match_symbol (&sym, 1);
+      if (m != MATCH_YES)
+	{
+	  gfc_error ("Expected name of allocator at %C");
+	  goto error;
+	}
+      gfc_symbol *allocator_sym = sym;
+
+      if (gfc_match_char ('(') == MATCH_YES)
+	{
+	  if (memspace_seen || traits_seen)
+	    {
+	      gfc_error ("Modifiers cannot be used with legacy "
+			 "array syntax at %C");
+	      goto error;
+	    }
+	  m = gfc_match_symbol (&sym, 1);
+	  if (m == MATCH_YES)
+	    traits_sym = sym;
+	  else
+	    goto error;
+	  if (gfc_match_char (')') != MATCH_YES)
+	    goto error;
+	}
+
+      if (traits_sym)
+	{
+	  if (traits_sym->ts.type != BT_DERIVED
+	      || strcmp (traits_sym->ts.u.derived->name,
+			 "omp_alloctrait") != 0
+	      || traits_sym->attr.flavor != FL_PARAMETER
+	      || traits_sym->as->rank != 1
+	      || traits_sym->value == NULL
+	      || !gfc_is_constant_expr (traits_sym->value))
+	    {
+	      gfc_error ("%<%s%> at %C must be of constant "
+			 "%<type(omp_alloctrait)%> array type and have a "
+			 "constant initializer", traits_sym->name);
+	      goto error;
+	    }
+	  gfc_set_sym_referenced (traits_sym);
+	}
+
+      if (memspace_sym)
+	{
+	  const char *pos;
+	  if (memspace_sym->ts.type != BT_INTEGER
+	      || memspace_sym->attr.flavor != FL_PARAMETER
+	      || mpz_cmp_si (memspace_handle_kind->value->value.integer,
+			     memspace_sym->ts.kind) != 0
+	      /* Check if identifier is of 'omp_..._mem_space' format.  */
+	      || (pos = strstr (memspace_sym->name, "omp_")) == NULL
+	      || pos != memspace_sym->name
+	      || (pos = strstr (memspace_sym->name, "_mem_space")) == NULL
+	      || *(pos + strlen ("_mem_space")) != '\0')
+	    {
+	      gfc_error ("%<%s%> at %C is not a pre-defined memory space name",
+			 memspace_sym->name);
+	      goto error;
+	    }
+	}
+
+      if (allocator_sym->ts.type != BT_INTEGER
+	  || mpz_cmp_si (allocator_handle_kind->value->value.integer,
+			 allocator_sym->ts.kind) != 0)
+	{
+	  gfc_error ("%<%s%> at %C must be integer of %<%s%> kind",
+		     allocator_sym->name, allocator_handle_kind->name);
+	  goto error;
+	}
+
+      if (allocator_sym->attr.flavor == FL_PARAMETER)
+	{
+	  const char *pos;
+	  /* Check if identifier is a 'omp_..._mem_alloc' pre-defined
+	     allocator.  */
+	  if ((pos = strstr (allocator_sym->name, "omp_")) == NULL
+	      || pos != allocator_sym->name
+	      || (pos = strstr (allocator_sym->name, "_mem_alloc")) == NULL
+	      || *(pos + strlen ("_mem_alloc")) != '\0')
+	    {
+	      gfc_error ("%<%s%> at %C is not a pre-defined memory allocator",
+			 allocator_sym->name);
+	      goto error;
+	    }
+
+	  /* Currently for pre-defined allocators in libgomp, we do not
+	     require additional init/fini inside target regions,
+	     so do nothing here to discard such clauses.  */
+	}
+      else
+	{
+	  gfc_set_sym_referenced (allocator_sym);
+
+	  gfc_omp_namelist *n = gfc_get_omp_namelist ();
+	  n->sym = allocator_sym;
+	  n->memspace_sym = memspace_sym;
+	  n->traits_sym = traits_sym;
+	  n->where = gfc_current_locus;
+
+	  n->next = c->lists[OMP_LIST_USES_ALLOCATORS];
+	  c->lists[OMP_LIST_USES_ALLOCATORS] = n;
+	}
+
+      if (gfc_match (" , ") == MATCH_YES)
+	{
+	  if (memspace_seen || traits_seen)
+	    {
+	      gfc_error ("When using modifiers, only a single allocator can be "
+			 "specified in each %<uses_allocators%> clause at %C");
+	      goto error;
+	    }
+	}
+      else
+	break;
+
+      memspace_sym = NULL;
+      traits_sym = NULL;
+    }
+
+  if (gfc_match_char (')') != MATCH_YES)
+    goto error;
+
+  return MATCH_YES;
+
+ error:
+  return MATCH_ERROR;
+}
 
 /* Match with duplicate check. Matches 'name'. If expr != NULL, it
    then matches '(expr)', otherwise, if open_parens is true,
@@ -2924,6 +3157,9 @@  gfc_match_omp_clauses (gfc_omp_clauses **cp, const omp_mask mask,
 		   ("use_device_addr (", &c->lists[OMP_LIST_USE_DEVICE_ADDR],
 		    false, NULL, NULL, true) == MATCH_YES)
 	    continue;
+	  if ((mask & OMP_CLAUSE_USES_ALLOCATORS)
+	      && gfc_match_omp_clause_uses_allocators (c) == MATCH_YES)
+	    continue;
 	  break;
 	case 'v':
 	  /* VECTOR_LENGTH must be matched before VECTOR, because the latter
@@ -3650,7 +3886,7 @@  cleanup:
    | OMP_CLAUSE_FIRSTPRIVATE | OMP_CLAUSE_DEFAULTMAP			\
    | OMP_CLAUSE_IS_DEVICE_PTR | OMP_CLAUSE_IN_REDUCTION			\
    | OMP_CLAUSE_THREAD_LIMIT | OMP_CLAUSE_ALLOCATE			\
-   | OMP_CLAUSE_HAS_DEVICE_ADDR)
+   | OMP_CLAUSE_HAS_DEVICE_ADDR | OMP_CLAUSE_USES_ALLOCATORS)
 #define OMP_TARGET_DATA_CLAUSES \
   (omp_mask (OMP_CLAUSE_DEVICE) | OMP_CLAUSE_MAP | OMP_CLAUSE_IF	\
    | OMP_CLAUSE_USE_DEVICE_PTR | OMP_CLAUSE_USE_DEVICE_ADDR)
@@ -6282,7 +6518,7 @@  resolve_omp_clauses (gfc_code *code, gfc_omp_clauses *omp_clauses,
 	"IN_REDUCTION", "TASK_REDUCTION",
 	"DEVICE_RESIDENT", "LINK", "USE_DEVICE",
 	"CACHE", "IS_DEVICE_PTR", "USE_DEVICE_PTR", "USE_DEVICE_ADDR",
-	"NONTEMPORAL", "ALLOCATE", "HAS_DEVICE_ADDR" };
+	"NONTEMPORAL", "ALLOCATE", "HAS_DEVICE_ADDR", "USES_ALLOCATORS" };
   STATIC_ASSERT (ARRAY_SIZE (clause_names) == OMP_LIST_NUM);
 
   if (omp_clauses == NULL)
diff --git a/gcc/fortran/trans-array.cc b/gcc/fortran/trans-array.cc
index 05134952db4..a2a2b889d03 100644
--- a/gcc/fortran/trans-array.cc
+++ b/gcc/fortran/trans-array.cc
@@ -6343,10 +6343,8 @@  gfc_conv_array_initializer (tree type, gfc_expr * expr)
 			       &expr->where, flag_max_array_constructor);
 	      return NULL_TREE;
 	    }
-          if (mpz_cmp_si (c->offset, 0) != 0)
-            index = gfc_conv_mpz_to_tree (c->offset, gfc_index_integer_kind);
-          else
-            index = NULL_TREE;
+
+	  index = gfc_conv_mpz_to_tree (c->offset, gfc_index_integer_kind);
 
 	  if (mpz_cmp_si (c->repeat, 1) > 0)
 	    {
diff --git a/gcc/fortran/trans-openmp.cc b/gcc/fortran/trans-openmp.cc
index 43d59abe9e0..1a3b1d5c347 100644
--- a/gcc/fortran/trans-openmp.cc
+++ b/gcc/fortran/trans-openmp.cc
@@ -2686,9 +2686,16 @@  gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 		    if (n->expr)
 		      {
 			tree allocator_;
-			gfc_init_se (&se, NULL);
-			gfc_conv_expr (&se, n->expr);
-			allocator_ = gfc_evaluate_now (se.expr, block);
+			if (n->expr->expr_type == EXPR_VARIABLE)
+			  allocator_
+			    = gfc_trans_omp_variable (n->expr->symtree->n.sym,
+						      false);
+			else
+			  {
+			    gfc_init_se (&se, NULL);
+			    gfc_conv_expr (&se, n->expr);
+			    allocator_ = gfc_evaluate_now (se.expr, block);
+			  }
 			OMP_CLAUSE_ALLOCATE_ALLOCATOR (node) = allocator_;
 		      }
 		    omp_clauses = gfc_trans_add_clause (node, omp_clauses);
@@ -3657,6 +3664,29 @@  gfc_trans_omp_clauses (stmtblock_t *block, gfc_omp_clauses *clauses,
 	      omp_clauses = gfc_trans_add_clause (node, omp_clauses);
 	    }
 	  break;
+	case OMP_LIST_USES_ALLOCATORS:
+	  for (; n != NULL; n = n->next)
+	    {
+	      tree allocator = gfc_trans_omp_variable (n->sym, false);
+	      tree memspace = (n->memspace_sym
+			       ? gfc_conv_constant_to_tree (n->memspace_sym->value)
+			       : NULL_TREE);
+	      tree traits = (n->traits_sym
+			     ? gfc_trans_omp_variable (n->traits_sym, false)
+			     : NULL_TREE);
+
+	      tree nc = build_omp_clause (input_location, OMP_CLAUSE_PRIVATE);
+	      OMP_CLAUSE_DECL (nc) = allocator;
+	      omp_clauses = gfc_trans_add_clause (nc, omp_clauses);
+
+	      nc = build_omp_clause (input_location,
+				     OMP_CLAUSE_USES_ALLOCATORS);
+	      OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (nc) = allocator;
+	      OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (nc) = memspace;
+	      OMP_CLAUSE_USES_ALLOCATORS_TRAITS (nc) = traits;
+	      omp_clauses = gfc_trans_add_clause (nc, omp_clauses);
+	    }
+	  break;
 	default:
 	  break;
 	}
diff --git a/gcc/fortran/types.def b/gcc/fortran/types.def
index cd79ad45167..18a1bec8724 100644
--- a/gcc/fortran/types.def
+++ b/gcc/fortran/types.def
@@ -81,6 +81,7 @@  DEF_FUNCTION_TYPE_0 (BT_FN_UINT, BT_UINT)
 DEF_FUNCTION_TYPE_0 (BT_FN_VOID, BT_VOID)
 
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_PTR, BT_VOID, BT_PTR)
+DEF_FUNCTION_TYPE_1 (BT_FN_VOID_PTRMODE, BT_VOID, BT_PTRMODE)
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_PTRPTR, BT_VOID, BT_PTR_PTR)
 DEF_FUNCTION_TYPE_1 (BT_FN_VOID_VPTR, BT_VOID, BT_VOLATILE_PTR)
 DEF_FUNCTION_TYPE_1 (BT_FN_INT_INT, BT_INT, BT_INT)
@@ -154,6 +155,8 @@  DEF_FUNCTION_TYPE_3 (BT_FN_VOID_SIZE_SIZE_PTR, BT_VOID, BT_SIZE, BT_SIZE,
 DEF_FUNCTION_TYPE_3 (BT_FN_UINT_UINT_PTR_PTR, BT_UINT, BT_UINT, BT_PTR, BT_PTR)
 DEF_FUNCTION_TYPE_3 (BT_FN_PTR_SIZE_SIZE_PTRMODE,
 		     BT_PTR, BT_SIZE, BT_SIZE, BT_PTRMODE)
+DEF_FUNCTION_TYPE_3 (BT_FN_PTRMODE_PTRMODE_INT_PTR, BT_PTRMODE, BT_PTRMODE,
+		     BT_INT, BT_PTR)
 
 DEF_FUNCTION_TYPE_4 (BT_FN_VOID_OMPFN_PTR_UINT_UINT,
                      BT_VOID, BT_PTR_FN_VOID_PTR, BT_PTR, BT_UINT, BT_UINT)
diff --git a/gcc/gimplify.cc b/gcc/gimplify.cc
index 2588824dce2..48a070443ba 100644
--- a/gcc/gimplify.cc
+++ b/gcc/gimplify.cc
@@ -9148,6 +9148,10 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
   hash_map<tree_operand_hash, tree> *struct_map_to_clause = NULL;
   hash_map<tree_operand_hash, tree *> *struct_seen_clause = NULL;
   hash_set<tree> *struct_deref_set = NULL;
+
+  hash_set<tree> *allocate_clauses = NULL;
+  hash_set<tree> *uses_allocators_allocators = NULL;
+
   tree *prev_list_p = NULL, *orig_list_p = list_p;
   int handled_depend_iterators = -1;
   int nowait = -1;
@@ -9185,6 +9189,13 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
       || code == OMP_TARGET_EXIT_DATA)
     omp_target_reorder_clauses (list_p);
 
+  if (code == OMP_TARGET
+      && (omp_requires_mask & OMP_REQUIRES_DYNAMIC_ALLOCATORS) == 0)
+    {
+      allocate_clauses = new hash_set<tree> ();
+      uses_allocators_allocators = new hash_set<tree> ();
+    }
+
   while ((c = *list_p) != NULL)
     {
       bool remove = false;
@@ -10884,6 +10895,18 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 	    OMP_CLAUSE_ALLOCATE_ALLOCATOR (c)
 	      = get_initialized_tmp_var (OMP_CLAUSE_ALLOCATE_ALLOCATOR (c),
 					 pre_p, NULL, false);
+	  if (allocate_clauses
+	      && OMP_CLAUSE_ALLOCATE_ALLOCATOR (c)
+	      && DECL_P (OMP_CLAUSE_ALLOCATE_ALLOCATOR (c))
+	      && !allocate_clauses->contains (c))
+	    allocate_clauses->add (c);
+	  break;
+
+	case OMP_CLAUSE_USES_ALLOCATORS:
+	  decl = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+	  if (uses_allocators_allocators
+	      && !uses_allocators_allocators->contains (decl))
+	    uses_allocators_allocators->add (decl);
 	  break;
 
 	case OMP_CLAUSE_DEFAULT:
@@ -10936,6 +10959,26 @@  gimplify_scan_omp_clauses (tree *list_p, gimple_seq *pre_p,
 	list_p = &OMP_CLAUSE_CHAIN (c);
     }
 
+  if (code == OMP_TARGET
+      && (omp_requires_mask & OMP_REQUIRES_DYNAMIC_ALLOCATORS) == 0)
+    {
+      for (hash_set<tree>::iterator i = allocate_clauses->begin ();
+	   i != allocate_clauses->end (); ++i)
+	{
+	  tree allocator = OMP_CLAUSE_ALLOCATE_ALLOCATOR (*i);
+	  if (uses_allocators_allocators->contains (allocator))
+	    continue;
+
+	  error_at (OMP_CLAUSE_LOCATION (*i),
+		    "allocator %<%qE%>in %<allocate%> clause on target region "
+		    "is missing %<uses_allocators(%E)%> clause",
+		    DECL_NAME (allocator), DECL_NAME (allocator));
+	}
+
+      delete allocate_clauses;
+      delete uses_allocators_allocators;
+    }
+
   ctx->clauses = *orig_list_p;
   gimplify_omp_ctxp = ctx;
   if (struct_seen_clause)
@@ -14165,6 +14208,79 @@  gimplify_omp_workshare (tree *expr_p, gimple_seq *pre_p)
 	  body = NULL;
 	  gimple_seq_add_stmt (&body, g);
 	}
+      else if ((ort & ORT_TARGET) != 0 && (ort & ORT_ACC) == 0)
+	{
+	  gimple_seq init_seq = NULL;
+	  gimple_seq fini_seq = NULL;
+
+	  tree omp_init_allocator_fn
+	    = builtin_decl_explicit (BUILT_IN_OMP_INIT_ALLOCATOR);
+	  tree omp_destroy_allocator_fn
+	    = builtin_decl_explicit (BUILT_IN_OMP_DESTROY_ALLOCATOR);
+
+	  for (tree *cp = &OMP_CLAUSES (expr); *cp != NULL;)
+	    if (OMP_CLAUSE_CODE (*cp) == OMP_CLAUSE_USES_ALLOCATORS)
+	      {
+		tree c = *cp;
+		tree allocator = OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (c);
+		tree memspace = OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (c);
+		tree traits = OMP_CLAUSE_USES_ALLOCATORS_TRAITS (c);
+		tree ntraits
+		  = ((traits
+		      && DECL_INITIAL (traits)
+		      && TREE_CODE (DECL_INITIAL (traits)) == CONSTRUCTOR)
+		     ? build_int_cst (integer_type_node,
+				      CONSTRUCTOR_NELTS (DECL_INITIAL (traits)))
+		     : integer_zero_node);
+		tree traits_var
+		  = (traits != NULL_TREE
+		     ? get_initialized_tmp_var (DECL_INITIAL (traits),
+						&init_seq, NULL)
+		     : null_pointer_node);
+
+		tree memspace_var = create_tmp_var (pointer_sized_int_node,
+						    "memspace_enum");
+		if (memspace == NULL_TREE)
+		  memspace = build_int_cst (pointer_sized_int_node, 0);
+		else
+		  memspace = fold_convert (pointer_sized_int_node,
+					   memspace);
+		g = gimple_build_assign (memspace_var, memspace);
+		gimple_seq_add_stmt (&init_seq, g);
+
+		/*
+		gimplify_assign (memspace_var,
+				 fold_convert (pointer_sized_int_node,
+					       memspace),
+				 &init_seq);
+		*/
+		tree initcall = build_call_expr_loc (OMP_CLAUSE_LOCATION (c),
+						     omp_init_allocator_fn, 3,
+						     memspace_var,
+						     ntraits,
+						     traits_var);
+		initcall = fold_convert (TREE_TYPE (allocator), initcall);
+		gimplify_assign (allocator, initcall, &init_seq);
+
+		g = gimple_build_call (omp_destroy_allocator_fn, 1, allocator);
+		gimple_seq_add_stmt (&fini_seq, g);
+
+		/* Finished generating runtime calls, remove USES_ALLOCATORS
+		   clause.  */
+		*cp = OMP_CLAUSE_CHAIN (c);
+	      }
+	    else
+	      cp = &OMP_CLAUSE_CHAIN (*cp);
+
+	  if (fini_seq)
+	    {
+	      gbind *bind = as_a<gbind *> (gimple_seq_first_stmt (body));
+	      g = gimple_build_try (gimple_bind_body (bind),
+				    fini_seq, GIMPLE_TRY_FINALLY);
+	      gimple_seq_add_stmt (&init_seq, g);
+	      gimple_bind_set_body (bind, init_seq);
+	    }
+	}
     }
   else
     gimplify_and_add (OMP_BODY (expr), &body);
diff --git a/gcc/omp-builtins.def b/gcc/omp-builtins.def
index cfa6483c7ae..e3103cea1c3 100644
--- a/gcc/omp-builtins.def
+++ b/gcc/omp-builtins.def
@@ -76,6 +76,10 @@  DEF_GOMP_BUILTIN (BUILT_IN_OMP_GET_TEAM_NUM, "omp_get_team_num",
 		  BT_FN_INT, ATTR_CONST_NOTHROW_LEAF_LIST)
 DEF_GOMP_BUILTIN (BUILT_IN_OMP_GET_NUM_TEAMS, "omp_get_num_teams",
 		  BT_FN_INT, ATTR_CONST_NOTHROW_LEAF_LIST)
+DEF_GOMP_BUILTIN (BUILT_IN_OMP_INIT_ALLOCATOR, "omp_init_allocator",
+		  BT_FN_PTRMODE_PTRMODE_INT_PTR, ATTR_NOTHROW_LEAF_LIST)
+DEF_GOMP_BUILTIN (BUILT_IN_OMP_DESTROY_ALLOCATOR, "omp_destroy_allocator",
+		  BT_FN_VOID_PTRMODE, ATTR_NOTHROW_LEAF_LIST)
 
 DEF_GOMP_BUILTIN (BUILT_IN_GOMP_ATOMIC_START, "GOMP_atomic_start",
 		  BT_FN_VOID, ATTR_NOTHROW_LEAF_LIST)
diff --git a/gcc/testsuite/c-c++-common/gomp/uses_allocators-1.c b/gcc/testsuite/c-c++-common/gomp/uses_allocators-1.c
new file mode 100644
index 00000000000..3288181b1ec
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/uses_allocators-1.c
@@ -0,0 +1,46 @@ 
+/* { dg-do compile } */
+/* { dg-additional-options "-fdump-tree-original -fdump-tree-gimple" } */
+
+#include <omp.h>
+
+omp_alloctrait_key_t k;
+omp_alloctrait_value_t v;
+
+int main (void)
+{
+  omp_allocator_handle_t foo, bar;
+  const omp_alloctrait_t foo_traits[] = { { omp_atk_pinned,    omp_atv_true },
+  					  { omp_atk_partition, omp_atv_nearest } };
+  #pragma omp target
+    ;
+  #pragma omp target uses_allocators (bar)
+    ;
+  #pragma omp target uses_allocators (foo (foo_traits))
+    ;
+  #pragma omp target uses_allocators (foo (foo_traits), bar (foo_traits))
+    ;
+  #pragma omp target uses_allocators (memspace(omp_high_bw_mem_space) : foo)
+    ;
+  #pragma omp target uses_allocators (traits(foo_traits) : bar)
+    ;
+  #pragma omp target uses_allocators (memspace(omp_high_bw_mem_space), traits(foo_traits) : bar)
+    ;
+  #pragma omp target uses_allocators (traits(foo_traits), memspace(omp_high_bw_mem_space) : bar) uses_allocators(foo)
+  {
+    void *p = omp_alloc ((unsigned long) 32, bar);
+    omp_free (p, bar);
+  }
+  return 0;
+}
+
+/* { dg-final { scan-tree-dump "pragma omp target" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(foo\\) uses_allocators\\(foo: memspace\\(\\), traits\\(foo_traits\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(foo_traits\\)\\) private\\(foo\\) uses_allocators\\(foo: memspace\\(\\), traits\\(foo_traits\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(foo\\) uses_allocators\\(foo: memspace\\(omp_high_bw_mem_space\\), traits\\(\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(foo_traits\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(omp_high_bw_mem_space\\), traits\\(foo_traits\\)\\)" "original" } } */
+/* { dg-final { scan-tree-dump "pragma omp target private\\(foo\\) uses_allocators\\(foo: memspace\\(\\), traits\\(\\)\\) private\\(bar\\) uses_allocators\\(bar: memspace\\(omp_high_bw_mem_space\\), traits\\(foo_traits\\)\\)" "original" } } */
+
+/* { dg-final { scan-tree-dump-times "__builtin_omp_init_allocator" 9 "gimple" } } */
+/* { dg-final { scan-tree-dump-times "__builtin_omp_destroy_allocator" 9 "gimple" } } */
diff --git a/gcc/testsuite/c-c++-common/gomp/uses_allocators-2.c b/gcc/testsuite/c-c++-common/gomp/uses_allocators-2.c
new file mode 100644
index 00000000000..74f411360c1
--- /dev/null
+++ b/gcc/testsuite/c-c++-common/gomp/uses_allocators-2.c
@@ -0,0 +1,32 @@ 
+/* { dg-do compile } */
+
+#include <omp.h>
+
+omp_alloctrait_key_t k;
+omp_alloctrait_value_t v;
+
+int main (void)
+{
+  omp_allocator_handle_t foo, bar;
+  const omp_alloctrait_t traits_array[] = { { omp_atk_pinned,    omp_atv_true },
+					    { omp_atk_partition, omp_atv_nearest } };
+  #pragma omp target uses_allocators (baz) /* { dg-error "'baz' undeclared .first use in this function." } */
+    ;
+  #pragma omp target uses_allocators (foo (xyz)) /* { dg-error "'xyz' undeclared .first use in this function." } */
+    ;
+  #pragma omp target uses_allocators (foo (traits_array), baz (traits_array))
+    ;
+  #pragma omp target uses_allocators (memspace(omp_no_such_space) : foo) /* { dg-error "'omp_no_such_space' undeclared" } */
+    ;
+  #pragma omp target uses_allocators (memspace(1) : foo) /* { dg-error "expected '\\\)' before numeric constant" } */
+    ;
+  #pragma omp target uses_allocators (memspace(omp_no_such_space) : foo, bar) /* { dg-error "memspace modifier must be constant enum of 'omp_memspace_handle_t' type" } */
+    ;
+  #pragma omp target uses_allocators (traits(xyz) : bar)
+    ;
+  #pragma omp target uses_allocators (memspace(omp_high_bw_mem_space), traits(traits_array), memspace (omp_no_such_space) : bar) /* { dg-error "expected ':' before ',' token" } */
+    ;
+  #pragma omp target uses_allocators (traitz(traits_array), memspace(omp_high_bw_mem_space) : bar) uses_allocators(foo) /* { dg-error "'traitz' undeclared .first use in this function." } */
+    ;
+  return 0;
+}
diff --git a/gcc/testsuite/gfortran.dg/gomp/uses_allocators-1.f90 b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-1.f90
new file mode 100644
index 00000000000..8afe9c4c331
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-1.f90
@@ -0,0 +1,53 @@ 
+! { dg-do compile }
+! { dg-additional-options "-fdump-tree-original -fdump-tree-gimple" }
+
+program main
+  use omp_lib
+  implicit none
+  integer, allocatable :: arr(:)
+  integer (omp_allocator_handle_kind) :: bar, foo
+
+  type (omp_alloctrait), parameter :: traits_array(*) = &
+       [omp_alloctrait(omp_atk_pinned,omp_atv_true),&
+       omp_alloctrait(omp_atk_partition,omp_atv_nearest)]
+
+  !$omp target allocate(bar : arr) uses_allocators(bar)
+  block
+    allocate(arr(100))
+  end block
+
+  !$omp target uses_allocators(omp_default_mem_alloc)
+  block
+  end block
+
+  !$omp target uses_allocators(bar(traits_array), foo (traits_array))
+  block
+  end block
+
+  !$omp target uses_allocators(traits(traits_array) : bar)
+  block
+  end block
+
+  !$omp target uses_allocators(memspace (omp_low_lat_mem_space) : bar)
+  block
+  end block
+
+  !$omp target uses_allocators(memspace (omp_high_bw_mem_space), traits(traits_array) : bar)
+  block
+    use iso_c_binding
+    type(c_ptr) :: ptr
+    integer(c_size_t) :: sz = 32
+    ptr = omp_alloc (sz, bar)
+    call omp_free (ptr, bar)
+  end block
+
+end program main
+
+! { dg-final { scan-tree-dump "pragma omp target allocate\\(allocator\\(bar\\):arr\\) private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(\\)\\)" "original" } }
+! { dg-final { scan-tree-dump "pragma omp target" "original" } }
+! { dg-final { scan-tree-dump "pragma omp target private\\(foo\\) uses_allocators\\(foo: memspace\\(\\), traits\\(traits_array\\)\\) private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(traits_array\\)\\)" "original" } }
+! { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(\\), traits\\(traits_array\\)\\)" "original" } }
+! { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(.\\), traits\\(\\)\\)" "original" } }
+! { dg-final { scan-tree-dump "pragma omp target private\\(bar\\) uses_allocators\\(bar: memspace\\(.\\), traits\\(traits_array\\)\\)" "original" } }
+! { dg-final { scan-tree-dump-times "__builtin_omp_init_allocator" 6 "gimple" } }
+! { dg-final { scan-tree-dump-times "__builtin_omp_destroy_allocator" 6 "gimple" } }
diff --git a/gcc/testsuite/gfortran.dg/gomp/uses_allocators-2.f90 b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-2.f90
new file mode 100644
index 00000000000..530d604902f
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-2.f90
@@ -0,0 +1,44 @@ 
+! { dg-do compile }
+
+program main
+  use omp_lib
+  implicit none
+  integer (omp_allocator_handle_kind) :: bar, foo
+
+  type (omp_alloctrait), parameter :: traits_array(*) = &
+       [omp_alloctrait(omp_atk_pinned,omp_atv_true),&
+       omp_alloctrait(omp_atk_partition,omp_atv_nearest)]
+
+  !$omp target uses_allocators(omp_non_existant_alloc) ! { dg-error "'omp_non_existant_alloc' at .1. must be integer of 'omp_allocator_handle_kind' kind" }
+  block
+  end block
+
+  !$omp target uses_allocators(bar(traits_array), foo (traits_array), ) ! { dg-error "Expected name of allocator at .1." }
+  block
+  end block
+
+  !$omp target uses_allocators(traits(xyz) : bar) ! { dg-error "'xyz' at .1. must be of constant 'type.omp_alloctrait.' array type and have a constant initializer" }
+  block
+  end block
+
+  !$omp target uses_allocators(memspace(omp_non_existant_mem_space) : foo) ! { dg-error "'omp_non_existant_mem_space' at .1. is not a pre-defined memory space name" }
+  block
+  end block
+
+  !$omp target uses_allocators(traits(traits_array), traits(traits_array) : bar) ! { dg-error "Multiple traits modifiers at .1." }
+  block
+  end block
+
+  !$omp target uses_allocators(memspace(omp_default_mem_space), memspace(omp_default_mem_space) : foo) ! { dg-error "Multiple memspace modifiers at .1." }
+  block
+  end block
+
+  !$omp target uses_allocators(memspace(omp_default_mem_space), traits(traits_array), traits(traits_array) : foo) ! { dg-error "Only two modifiers are allowed on 'uses_allocators' clause at .1." }
+  block
+  end block
+
+  !$omp target uses_allocators(memspace(omp_default_mem_space), traits(traits_array) : foo, bar) ! { dg-error "When using modifiers, only a single allocator can be specified in each 'uses_allocators' clause at .1." }
+  block
+  end block
+
+end program main
diff --git a/gcc/testsuite/gfortran.dg/gomp/uses_allocators-3.f90 b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-3.f90
new file mode 100644
index 00000000000..064ccf455b1
--- /dev/null
+++ b/gcc/testsuite/gfortran.dg/gomp/uses_allocators-3.f90
@@ -0,0 +1,14 @@ 
+! { dg-do compile }
+
+program main
+  use omp_lib
+  implicit none
+  integer, allocatable :: arr(:)
+  integer (omp_allocator_handle_kind) :: bar
+
+  !$omp target allocate(bar : arr) ! { dg-error "allocator ''bar''in 'allocate' clause on target region is missing 'uses_allocators.bar.' clause" }
+  block
+    allocate(arr(100))
+  end block
+
+end program main
diff --git a/gcc/tree-core.h b/gcc/tree-core.h
index f1c2b6413a3..7ac0b47ac2d 100644
--- a/gcc/tree-core.h
+++ b/gcc/tree-core.h
@@ -522,6 +522,9 @@  enum omp_clause_code {
 
   /* OpenACC clause: nohost.  */
   OMP_CLAUSE_NOHOST,
+
+  /* OpenMP clause: uses_allocators.  */
+  OMP_CLAUSE_USES_ALLOCATORS,
 };
 
 #undef DEFTREESTRUCT
diff --git a/gcc/tree-pretty-print.cc b/gcc/tree-pretty-print.cc
index 99af977979d..a46db024157 100644
--- a/gcc/tree-pretty-print.cc
+++ b/gcc/tree-pretty-print.cc
@@ -769,6 +769,20 @@  dump_omp_clause (pretty_printer *pp, tree clause, int spc, dump_flags_t flags)
       pp_right_paren (pp);
       break;
 
+    case OMP_CLAUSE_USES_ALLOCATORS:
+      pp_string (pp, "uses_allocators(");
+      dump_generic_node (pp, OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR (clause),
+			 spc, flags, false);
+      pp_string (pp, ": memspace(");
+      dump_generic_node (pp, OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE (clause),
+			 spc, flags, false);
+      pp_string (pp, "), traits(");
+      dump_generic_node (pp, OMP_CLAUSE_USES_ALLOCATORS_TRAITS (clause),
+			 spc, flags, false);
+      pp_right_paren (pp);
+      pp_right_paren (pp);
+      break;
+
     case OMP_CLAUSE_AFFINITY:
       pp_string (pp, "affinity(");
       {
diff --git a/gcc/tree.cc b/gcc/tree.cc
index 4cf3785270b..973a8366372 100644
--- a/gcc/tree.cc
+++ b/gcc/tree.cc
@@ -349,6 +349,7 @@  unsigned const char omp_clause_num_ops[] =
   0, /* OMP_CLAUSE_IF_PRESENT */
   0, /* OMP_CLAUSE_FINALIZE */
   0, /* OMP_CLAUSE_NOHOST */
+  3, /* OMP_CLAUSE_USES_ALLOCATORS */
 };
 
 const char * const omp_clause_code_name[] =
@@ -439,6 +440,7 @@  const char * const omp_clause_code_name[] =
   "if_present",
   "finalize",
   "nohost",
+  "uses_allocators",
 };
 
 /* Unless specific to OpenACC, we tend to internally maintain OpenMP-centric
diff --git a/gcc/tree.h b/gcc/tree.h
index 8844471e9a5..bfe2cd82232 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1824,6 +1824,15 @@  class auto_suppress_location_wrappers
 #define OMP_CLAUSE_ALLOCATE_COMBINED(NODE) \
   (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_ALLOCATE)->base.public_flag)
 
+#define OMP_CLAUSE_USES_ALLOCATORS_ALLOCATOR(NODE) \
+  OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_USES_ALLOCATORS), 0)
+
+#define OMP_CLAUSE_USES_ALLOCATORS_MEMSPACE(NODE) \
+  OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_USES_ALLOCATORS), 1)
+
+#define OMP_CLAUSE_USES_ALLOCATORS_TRAITS(NODE) \
+  OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_USES_ALLOCATORS), 2)
+
 #define OMP_CLAUSE_NUM_TEAMS_UPPER_EXPR(NODE) \
   OMP_CLAUSE_OPERAND (OMP_CLAUSE_SUBCODE_CHECK (NODE, OMP_CLAUSE_NUM_TEAMS), 0)